Still trying to wrap my head around Sketch and how it works. I have a bunch of PNG screenshots (iPhone 8 resolution so 750px wide, or 375@2x) and I want to build a quick click-through prototype in Sketch. Seems simple enough... create artboards for the pages, drag the images onto the artboards, then use the 'Fit' button to size the artboard to the content (which changes the height since the widths already match.)
The weird thing is when using the 'Preview' feature, some artboards show full-width and scroll (as I would expect), while other artboards show the entire artboard, scaled down to fit so it's tiny with huge black bars on the sides.
Checking the inspector on both the artboards as well as the images, I don't see any difference between those that scroll vs. those that don't.
Of note, some were created using the iPhone 8 template whereas others I tried using 'from selection' to save time. But still, I don't see any difference in the resulting artboard.
So what am I missing? How do I get my artboard to scroll, not scale?